Sven Kleinstock (Earth-616)

Sven, Harlan, and Eric Kleinstocks are triplet mutants from the Switzerland.^[1] Under unknown circumstances they were recruited into the Acolytes, believing Magneto to be the savior of mutantkind. On their first mission with the Acolytes, the Kleinstock Brothers were sent alongside Cargill and Unuscione to kidnap a young mutant. During the mission, the Acolytes murdered Sharon Friedlander, a former staff member at Charles Xavier's School for Gifted Youngsters. Unbeknownst to the Acolytes, Friedlander's psionic cries for help to Xavier alerted the X-Men to their activities. In the ensuing battle, Eric Kleinstock was shot and killed by Tom Corsi, another staff member from Xavier's school. Harlan and Sven, seemingly unfazed by their brother's death, continued to battle and defeat Archangel until they were telekinetically slammed together by Jean Grey. Harlan and Sven then merged together into their gestalt form, simply called Kleinstock by Unuscione, and fought Bishop. After discovering their target was a child with Down's Syndrome, the Acolytes abandoned the mission and retreated.^[2]

Despite losing their brother, Harlan and Sven continued to serve with the Acolytes.^[3] They soon suspected Colossus of being a traitor to the Acolytes.^[4]

Sven survived Holocaust's destruction of Avalon alongside Harlan, Unuscione, and Cargill, and evacuated to Earth with Cyclops. The group crash landed in the Australian Outback, where they managed to get to the X-Men's former base of operations. Once help arrived, the Acolytes turned themselves over to the authorities.^[5]

Later, the Acolytes presumably escaped prison as they had returned to serve Magneto.^[6] Harlan and Sven later participated in the attack on Wundagore Mountain under the leadership of Exodus.^[7][8]

Magneto ordered Amelia Voght to separate the best of the Acolytes. The Kleinstocks were ordered to follow Fabian Cortez alongside Senyaka, Spoor, Projector, Rem-Ram, Static, and Barnacle as they attacked the X-Men's mansion. After the Acolytes were defeated, they asked for sanctuary with Xavier. Xavier denied them compassion after failing with Sabretooth.^[9]

Sven, Harlan, and the other rejected Acolytes later attacked Genosha. The brothers' former comrade Cargill ambushed the Kleinstocks, but the renegade Acolytes were empowered by Cortez and easily defeated the Genoshan forces. However, Cortez quickly betrayed the group and stopped amplifying their powers, allowing the Genoshan government to defeat them.^[10]

It is unknown if the Kleinstock Brothers retained their powers after Decimation.

Nightcrawler and a small team of X-Men later came across a statue of the Kleinstock Brothers alongside several other supervillains in an anti-mutant sanctuary run by Orchis.^[11]

• Joint Lifeform Fusion: Sven and Harlan can merge into one being, possessing double the size, strength, and toughness that they would as an individuals. In this form the brothers have a merged psyche.^[2] Since Kleinstocks were triplets, it is possible what Eric was also able to merge with Sven and Harlan.

• Plasma Generation: He can also generate plasma blasts from his hands.^[2]